Pulmonary alveolar type II cells can be isolated in sufficient numbers and in population of sufficient homogeniety to permit In Vitro morphologic and biochemical experimenation in a defined system. The specific aims of this proposal are (1) to determine if type II cells synthesize and/or secrete DSPC in direct response to principal effectors other than B-adrenergic catecholamines: and (2) to determine if the synthesis and/or secretion of DSPC by type II cells is also modulated indirectly by hormonal action on principal effectors. DSPC synthesis will be assayed by measuring the rates of incorporation of [14C[ - choline into cellular DSPC in the presence of varius hormones or combinations of hormones. DSPC secretion will be assayed by measuring the rate of secretion of [14C[ - choline into the culture medium. The hormones to be investigated are all agents which have been implicated in some way in pulmonary function. During the course of these experiments, B-adrenergic receptor density, affinity and specifically will be determined. Our long term objective is to clarify the pathogenesis of acute respiratory distress in the new born so that more effective therapies or preventive measures can be developed.